A gender disparity exists in asthma prevalence. As adults, women have an increased asthma prevalence compared to men. Many phenotypes of asthma exist, ranging from mild asthma with onset during childhood to severe asthma with later onset, making asthma a broad disease with different pathologies. As adults, women are more likely to have severe asthma and a later onset of asthma compared to men. In this article, we reviewed clinical studies and animal studies that showed:

Clinical studies

• During puberty, asthma symptoms increase in females compared to males.
• After puberty, the role for sex hormones in regulating asthma symptoms during menstruation, pregnancy, and menopause is unclear.

Animal studies

• Estrogen increases and testosterone decreases Th2-mediated airway inflammation, airway hyperresponsiveness to methacholine, and mucus production.
• Estrogen receptor β (ER-β) knockout mice have decreased AHR compared to estrogen receptor α (ER-α) and WT mice following OVA sensitization and challenge.
• IL-5 and IL-13 protein expression are increased in IL-33 stimulated innate lymphoid group 2 cells from WT female mice compared to male mice allergic airway inflammation. 
• Females have increased IL-17A-mediated airway inflammation compared to males.
• 17β-estradiol plus progesterone increased IL-17A production in Th17 cells by decreasing let-7f miRNA expression and increasing IL-23R expression.

Overall, ovarian hormones increased and testosterone decreased airway inflammation in asthma, but the exact mechanisms remain unclear. Delineating these pathways using animal models as well as women and men with various phenotypes of asthma will help determine if women with asthma should take (or avoid) hormonal contraceptives as well as predict changes in asthma symptoms during life phases, including pregnancy and menopause, when sex hormones are dramatically changing.